Long term readers may be aware that I love my Pentax K-x. It's one of the most compact and handy DSLR cameras you can get, but it's right up there in performance. My feeling is that that to get any palpable improvement in quality (especially if used with Pentax's excellent non-zoom lenses), you have to take a big jump up both in bulk and in price. (To, for example, the Canon 5D2 with L-lenses.)
The new K-r seems to improve on it in various ways, including higher ISO settings. The K-x's low-light performance was already very impressive, so this should prove interesting.
I also think the new black model looks more professional than the K-x.
Update: this article gives a lot more info. It looks like rather than an K-x replacement, the K-r is placed between the K-x and the professional K-7 in many ways. This also means it's not quite as compact as the K-x. I had hoped it would be as small, but on the other hand, I guess this means it's potentially stronger and has better handling.
I like that they have kept the sensor resolution, instead of like Canon to boost the resolution to insane numbers like 16 or 18 megapixels in a non-full-frame camera. (Which they have actually done with the new K-5. But that has a very high ISO limit, so it seems they are relaxed about performance per pixel.) With the 12 megapixels you have better potential for really good low-light (high-ISO) performance (less grain in the pictures in low light).
Altogether, I have no doubt this will be a very powerful camera for the serious amateur. And there's no reason many pros shouldn't use it either, unless you need to calm down big apes with a bump of a 3-kilo camera.